Materials discovery through crystal growth continues to be the best way to explore phase space in the quest for new or improved physical properties. Soft chemical methods allow for the investigation of regions of phase-space inaccessible via traditional synthetic routes.
Iron (III) is known to take on a tetrahedral coordination environment with oxygen in some of its compounds, though it predominately prefers an octahedral environment. Most often, these tetrahedra are isolated. However, some compounds have shown that FeO4 tetrahedra can be condensed into higher dimensional structures. A small number of compounds have shown FeO4 tetrahedra corner-shared to form various-membered rings such as AFeO2 (A=K, Rb and Cs), Ba4KFe3O9, Na14Fe6O16, and Ba3Fe2O6. This is not unlike what is observed in silicate chemistry, despite the obvious disparity between the two elements' propensity to form condensed frameworks.